This invention relates generally to an agricultural combine. It relates particularly to a residue handling system for an agricultural combine.
Agricultural combines are well-known machines for harvesting crop materials. They are available in various forms but all perform the basic functions of reaping crop materials from a field, separating grain from non-grain crop materials, and discarding the non-grain materials in the field.
A typical combine includes a crop harvesting or header assembly which reaps ripened crop plants from the crop field and a feeder assembly which feeds the crop materials to a threshing assembly. One type of combine incorporates a rotary threshing assembly. In such a combine, the crop materials are introduced to the front end of the rotary threshing assembly, which is oriented longitudinally, or axially, within the combine body. The crop materials are then threshed between a rotating rotor, which includes rasp bars along its exterior, and the inside of a rotor cylinder. Along the bottom of the rotor cylinder concaves are mounted that allow grain heads and other fine materials to pass through while retaining the crop stalks within the rotor cylinder.
The rotary threshing assembly includes mechanisms for feeding the crop materials rearwardly through the rotor assembly so that the crop stalks and other materials which do not pass through the concaves are discharged out the rear end of the assembly. The grain heads and other fine materials pass through the concaves onto a series of sieves that separate the grain from the unwanted fine materials. A cleaning fan directs air flow through the sieves to assist in the separation operation. After separation, the grain is conveyed to a grain bin through an auger system and the unwanted fine materials are discharged from the rear end of the sieves.
Modern farming practices require that the unwanted crop stalks be chopped up, mixed with fine materials, and evenly spread across the crop field. This is especially true with no-till farming, but is also important for more traditional farming techniques.
The demand for greater productivity has resulted in larger header assemblies, which harvest wider swaths in the crop field, and increased travelling speeds of the combine across the crop field. This has led to a need for more effective distribution systems for the non-grain crop materials.
A common type of non-grain or residue distribution system includes a residue chopper. The residue chopper is typically located in the rear of the combine body. Some types of residue choppers receive and distribute only crop stalks from the rotor assembly. Other types receive and distribute both crop stalks and fine materials from the sieves.
The residue chopper is oriented transversely of the combine and includes a plurality of flail blades which chop and mix the crop materials. The flail blades are pivotally connected to supports on a rotating hub. Normally, two flail blades are attached to each support, with one on each side of the support. In most prior art systems the two flail blades are spaced from the mounting support with spacer bushings. However, with such a construction, the mounting flange can become weak from continuously applied stresses and eventually break, causing unwanted downtime and repair costs. Additionally, use of these spacer bushings does not permit accurate positioning of the flail blades.
Air flow through the residue chopper greatly influences the effectiveness of the chopper in mixing the crop materials and distributing them from the rear of the combine. Vanes located at the exit of the residue chopper sweep in an outward direction to spread the crop materials across the crop field. Optimally, the crop materials will be discharged evenly in a swath which is the same width as the combine header assembly. However, because combine header assemblies can be as wide as thirty feet and more, the crop materials must exit the residue chopper at a high velocity in order to be directed across a wide swath. This necessitates a large volume of air flow through the residue chopper to achieve the desired exit velocity.
In residue choppers which receive both crop materials from the threshing assembly cylinder and fine materials from the sieves, it is a common practice to direct the cleaning fan air through the residue chopper. In this arrangement, the residue chopper housing becomes the primary path for the cleaning air, and the cleaning fan becomes the primary source of air flow through the residue chopper. The design and shape of the residue chopper""s flail blades is important in ensuring adequate air flow through the chopper. Some known flail blades inhibit air flow through the residue chopper and actually create back pressure that partially prevents the cleaning fan air flow from entering the chopper. This not only adversely affects exit velocity of the crop materials but also reduces the effectiveness of the cleaning fan in separating the grain from the non-grain fine and light materials.
It is a primary object of the invention to provide an improved residue chopper in a rotary combine.
It is also an object of the invention to provide an improved flail blade which assists the cleaning fan in moving air through the residue chopper.
It is another object to provide an improved flail blade which increases air flow through a residue chopper.
It is still another object to provide a flail blade which is configured intermediate its ends so that the front surface of the blade is inclined from the direction of blade travel in the chopper.
It is a further object of the invention to provide a mounting arrangement for the flail blades on a hub which includes a hollow mounting support having a width equal to the desired space between the inner ends of mated flail blades.
It is still a further object to provide a flail blade mounting arrangement which better resists fatigue stresses while providing more accurate flail blade positioning.
It is yet a further object to provide an improved hub and blade assembly in a residue chopper for a rotary combine.
It is yet another object to provide an improved hub and flail blade assembly including a pattern of flail blades which provides optimum residue distribution.
According to the invention, each flail blade is pivotally connected to a rotatable hub in a hub and blade assembly. An inner portion of the flail blade is flat and lies in a plane perpendicular to the axis of rotation of the hub. An outer portion of the blade is also flat, but is inclined from that plane. Thus, the front surface of the outer portion of the blade is inclined at an angle to the plane of rotation of the blade. As the blade rotates during operation of the chopper, this angled front surface increases the flow of air through the chopper housing by moving air ahead of it.
In a mated blade arrangement, two blades are attached to a single mounting support. In a first form of mated blade arrangement, the outer portions of the blades are angled in opposite directions so that the leading edges of the outer portions of two flail blades are closer to each other than the trailing edges. What amounts to a V-shaped pocket is formed behind the blades as they rotate. In a second form of mated blade arrangement, the trailing edges of the outer portions of mated blades are closer to each other than the trailing edges, creating a V-shaped pocket in front of the blades. In a third form of mated blade arrangement, the leading and trailing edges are equidistant from each other. A fixed knife attached to the housing passes between the leading edges of the mated blades when the hub rotates, producing a scissors cutting action to chop-up crop materials.
According to the invention, different forms of mated blade arrangements may be mounted on the same hub to create a pattern in the hub and blade assembly which produces a desired pattern of residue blown from the chopper. A hub and blade assembly may be effectively divided into three sections: a center section having the first and/or second form of blade arrangements thereon; a left section having the third form of blade arrangements thereon with the outer blade portions inclined so as to direct residue to the left as well as rearwardly; and, a right section having the third form of blade arrangements thereon with outer blade portions inclined so as to direct residue to the right as well as rearwardly.
The mounting support for each blade or mated pair of blades includes a rectangular cross-section post. The mounting support post has front, back, and side walls. The width of the post is substantially the same as the desired distance between the parallel inner portions of two mated flail blades, Therefore, the side surfaces of the inner portions on the flail blades directly contact the side walls of the mounting support post, without the need for spacer bushings. The flail blades can be pivotally mounted on the support post using only three mounting elements and a wrench.